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FEATURE ARTICLE: WOMEN OF CHILDBEARING AGE

Introduction

Health professionals recommend that women of childbearing age (16 to 44 years) maintain higher levels of some nutrients in order to best prepare for pregnancy. Women of this age are encouraged to boost their levels of folate, iodine and Vitamin B12, even before becoming pregnant, as these nutrients are vital for early fetal growth and development. Likewise, it is well documented that women of childbearing years are at increased risk of anaemia, which for pregnant women, can increase the chance of having a premature or low birth weight baby.1

In 2009, mandatory fortification of baked bread with iodised salt and bread-making flour with folic acid (the synthetic form of folate) was introduced in Australia.2 Given the critical importance of both of these nutrients in early pregnancy, women of childbearing years are a key target group for these programs.

The 2011–12 National Health Measures Survey (NHMS) included tests for folate, iodine, Vitamin B12 and ferritin (a measure of iron stores in the body). It is also a key data source for measuring the effectiveness of mandatory fortification in increasing folate and iodine levels within the population.

This article presents information on the nutrient status of women of childbearing age and looks at whether women's folate and iodine levels have changed in response to mandatory fortification.

Do women of childbearing age get the nutrients they need?

Folate is perhaps the most important vitamin for women of childbearing years, as it is essential for the prevention of neural tube defects (NTDs) in babies, most notably spina bifida.3 Given the critical importance of folate in early growth and development, it is recommended that all women of childbearing age, even if they are not planning on becoming pregnant, take extra folate.1Mandatory fortification of bread with folic acid was also introduced in Australia in 2009 to help prevent the incidence of NTDs.

The NHMS showed that the vast majority of women of childbearing age had sufficient folate levels in 2011–12. Less than 1% had a red cell folate level under 906 nmol/L, which indicates an increased risk of NTDs and no women aged 16–44 years were in the range for high risk of NTDs (<453 nmol/L).4

Vitamin B12 also plays an important role in folate levels, as B12 deficiency can interfere with the body's ability to effectively use folate.5 Women of childbearing age had adequate levels of Vitamin B12 in 2011–12, with an average of 359.7 pmol/L, which is well above the WHO cut-off for Vitamin B12 deficiency (150 pmo/L).6

However, the story was slightly different for iodine. It is recommended that women of childbearing age have a higher iodine intake than the general population, so to protect against fetal developmental disorders if they were to become pregnant.7Mandatory fortification of bread with iodised salt was also introduced in 2009 to address the re-emergence of iodine deficiency in the population.2

Although women aged 16–44 years had sufficient iodine levels overall in 2011–12 (a median urinary iodine concentration (UIC) of 121.0 µg/L, which is above the WHO recommended level of 100 µg/L), one in every five (18.3%) had iodine levels under 50 µg/L, which is the WHO cut-off for moderate iodine deficiency.8 Likewise, nearly two thirds (62.2%) had an iodine level less than 150 µg/L, which is the recommended level for all women who are pregnant, breastfeeding or considering pregnancy.8 These results suggest that mandatory fortification may not be enough to meet the additional iodine requirements of these women. For more information on iodine status in Australia, see the Iodine feature article.